This invention is directed toward a method and means of adjusting or zeroing in a scope on a firearm. More specifically to adjusting or zeroing in a variety of different types of scopes with a variety of scope divisions of minute of angle (MOA's) under a variety of conditions.
Scopes are often mounted to a firearm to improve the firearm's accuracy. In using the scope to its fullest extent, a user must properly site the scope. In general, sighting of the scope involves zeroing the scope at a firing range or in the field to align the center point of the scope reticle with the impact location of the projectile. After zeroing the scope, the scope may be later adjusted for other conditions. Other conditions include any number of variables, including changes in wind conditions, parabolic drop, ballistic coefficients, bullet type, grain type, or the like. The most common of these conditions are wind conditions and parabolic drop. In both zeroing the scope and adjusting for these conditions, the scope is adjusted horizontally and vertically. Any horizontal adjustment is known as windage in the art; likewise, any vertical adjustment is known as elevation in the art.
As noted above, sighting of the scope often involves adjusting for other conditions. While these adjustments are related to efficient sighting of the scope, they are not directly related to zeroing the scope. Typically, a scope is zeroed first, then adjustments are made in the field from this zeroed position to adjust the scope for changes in conditions such as changes in wind conditions (affecting the horizontal path of the projectile) and parabolic drop (affecting the elevational path of the projectile). Many devices have been designed to adjust the scope for changes in wind conditions and parabolic drop in the field; however, these devices fail to provide a simple apparatus or method for zeroing the scope in the field.
Zeroing of the scope, as explained below is typically performed at a pre-determined distance of 25, 50, 75 or 100 yards or meters (at a firing range for example). During zeroing of the scope based on the pre-determined distance, a sighting shot or multiple sighting shots are delivered to a target. The vertical and horizontal shot placement spacing of the sighting shot (or a triangulated center of multiple sighting shots) from the target center point determines the adjustment needed for the specific scope to be properly zeroed. Scopes are typically adjusted based on one minute of angle, or divisions thereof. By coincidence, the width of one minute of angle of a degree at a radius of 100 yards is almost exactly one inch (1.0476 inches) or approximately 28 millimeters at 100 meters; likewise, one minute of angle at 200 yards is almost exactly two inches or approximately 56 millimeters. For example, a sighting shot at a distance of 100 yards striking a target 2 inches below and 3 inches to the right of the target center point requires a two minute of angle adjustment up and a three minute of angle adjustment to the left to properly zero the scope based on the predetermined distance of the test shot, and the type of scope used.
While this method is very accurate for zeroing the scope, it is problematic to apply in the field and to multiple scopes under multiple test distances. Specifically, without the benefit of the specific instructions for a specific scope at a pre-determined distance, one must recall the mathematical relationship between the distance to target, the shot placement spacing of the sighting shot (or shots) from the target center point, and the adjustment made to the specific type of scope required to zero in the scope.
In view of these problems, it is the object of this invention to provide a simple method and means for zeroing the scope based on the distance from a target, the shot placement spacing from the target center point, and the division of minute of angle adjustment available on the particular scope.
These and other objects will be apparent to those skilled in the art.